The subject invention relates to performing catheter-based diagnostic or therapeutic procedures within the lung. In particular, the invention relates to closing or partially closing intercommunicating channels within the lung in order to prevent a target lung compartment from receiving collateral ventilation through such intercommunicating secondary channels.
The lung consists of a left lung and right lung having two and three lobes respectively (FIG. 1). Air is delivered into and out of the lobes of the lungs through a bronchial system comprising tubular airways starting with the trachea which divides and subdivides until the airways reach the periphery of the lobes terminating in long lobules which contain the alveoli. In a normal lung, the tissue of each lobe is physically separated from that of other lobes, the separation being referred to as a fissure. This fissure prevents the passage of air between neighboring lobes. However, for reasons not fully understood, the fissures separating the lobes are sometimes absent or incomplete, allowing the collateral flow of air between neighboring lobes. At the periphery of a given lobe within the lung, there exist channels or pores that interconnect alveoli or terminal bronchioles from one bronchial tree branch to the alveoli or terminal bronchioles belonging to the neighboring bronchial tree branch.
In some disease states, such interconnections at the lung lobule level and/or connections through incomplete fissures can become more pronounced, rendering certain treatments problematic. For example, emphysema may be treated by minimally invasive lung volume reduction (LVR) where feeding airways that deliver air to diseased hyperinflated lung lobes or segments within a lobe are plugged or otherwise occluded to prevent re-inflation. However, if collateral interconnections exist, LVR can be hampered since the collapsed region can re-inflate through any collateral connection.
Proposed treatments to circumvent this problem include permanently shrinking the targeted region, lobe or lobe segment, such as by ablating, heating, mechanically compressing with an implant, or the like. In such treatments, collateral leakage is immaterial since reinflation of the treated area is physically prevented by nature of the treatment. These treatments, however, are destructive and have not yet achieved good, safe results and are considered undesirable.
Therefore, in the case of minimally invasive lung volume reduction for emphysema treatment it would be desirable to partially or completely block or close collateral passages and pathways which allow collateral ventilation with adjacent regions.
One such method is described in published US Patent Application 2003/0228344 which proposes injecting an agent bronchscopically, transthoracically or by puncturing a bronchial wall, to close the collateral channels while using a one-way valve in an airway to control the air flow path so that the deposition of the agent is directed into the collateral channels. Unfortunately, this technique has a significant disadvantage in that the targeting of the agent is poorly controlled with the methods they describe. Pressure differentials, created by use of a bronchial one-way valve or applying vacuum transthoracically to a lung area, allow the agent to mix and spread to unwanted areas. An additional disadvantage of this technique is that the user must perform lung volume reduction on the patient by implanting bronchial valves or occluders in order to diagnose whether or not the patient possess collateral channels. If the patient does not develop lung area deflation by gas absorption, or absorption atelectasis, then it is concluded there are collateral channels and the patient requires the collateral channel treatment. This is a very inconvenient treatment protocol.
As will be described in the subsequent sections, the present invention solves at least some of the deficiencies of such prior art techniques.